SANTA CLARA – The 49ers have two players in their contract years who could command big-money deals as free agents.

General manager Trent Baalke said the 49ers will attempt to sign guard Mike Iupati and wide receiver Michael Crabtree to contract extensions before they become unrestricted free agents next spring.

The sides are not believed to be remotely close to new contracts for either Iupati or Crabtree, according to multiple sources.

“We’re going to try,” Baalke said. “We’re going to work at it, certainly. But at some point, you got to stop negotiating deals and let these guys concentrate on playing football. I don’t know what point that is. We’ll make that determination as a club.

“But we’re certainly going to work toward that goal. Those are two very good football players, and guys we’d love to have in this organization for the long term.”

The 49ers signed tackles Joe Staley and Anthony Davis to new contracts within the past 16 months. In order to stay consistent with the team’s salary structure, the 49ers might not want to exceed Staley’s $7.44 million annual average or Davis’ $6.52 million average on a deal for a guard -- even a two-time Pro Bowl performer, such as Iupati.

Crabtree has looked good in training camp after being limited last season due to a torn Achilles. He could take a step toward being regarded as an elite NFL receiver. With a strong season, he could fetch a lucrative contract. If he hits the open market, it might be difficult for the 49ers to retain him. Crabtree missed the first five games of his NFL career in a contract dispute after being the No. 10 overall pick in the 2009 draft.

The 49ers have the franchise tag available for next season. This year, the franchise number for a wide receiver was $12.312 million, while the tag was $11.654 for an offensive lineman. Some increase can be expected next season.